Medicare Part D.

In plain English

Medicare Part D is prescription-drug coverage. It is not built into Original Medicare; you buy it as a stand-alone plan from a private insurer, or you get it bundled inside a Medicare Advantage (Part C) plan. Each plan has its own formulary, which is the list of drugs it covers and the price tier for each one. You pay a monthly premium, often a deductible, and then a share of each prescription until you hit the plan's yearly out-of-pocket limit, after which your covered drugs cost much less.

01Why it matters

If you go without Part D or other creditable drug coverage when you first qualify, you can owe a late-enrollment penalty that gets added to your premium permanently. Picking a plan whose formulary actually covers your medications can mean the difference of hundreds of dollars a year.

02The math, step by step

Suppose you take one brand-name medication. You would check each Part D plan's formulary to see what tier your drug falls in and what copay applies, then weigh that against the plan's monthly premium. For 2026, no Part D plan may charge a deductible above $615, and once your out-of-pocket spending on covered drugs reaches $2,100 you reach catastrophic coverage and pay nothing more for covered drugs that year.

03What this is NOT

04Receipts

Every figure on this page is sourced to a primary document. Tap to open the original.